import { saveAs } from 'file-saver'
// import Blob from './blob'
import * as XLSX from 'xlsx'
import * as XLSXS from 'xlsx-style-vite'

/**
 * 将HTML表格转换为二维数组
 * @param {*} table
 * 函数支持处理表格中的单元格合并、行列跨度以及特定数据类型转换
 */
function generateArray(table) {
  var out = [];
  var rows = table.querySelectorAll('tr');
  var ranges = [];
  for (var R = 0; R < rows.length; ++R) {
    var outRow = [];
    var row = rows[R];
    var columns = row.querySelectorAll('td');
    for (var C = 0; C < columns.length; ++C) {
      var cell = columns[C];
      var colspan = cell.getAttribute('colspan');
      var rowspan = cell.getAttribute('rowspan');
      var cellValue = cell.innerText;
      if (cellValue !== "" && cellValue == +cellValue) cellValue = +cellValue;

      //Skip ranges
      ranges.forEach(function (range) {
        if (R >= range.s.r && R <= range.e.r && outRow.length >= range.s.c && outRow.length <= range.e.c) {
          for (var i = 0; i <= range.e.c - range.s.c; ++i) outRow.push(null);
        }
      });

      //Handle Row Span
      if (rowspan || colspan) {
        rowspan = rowspan || 1;
        colspan = colspan || 1;
        ranges.push({
          s: {
            r: R,
            c: outRow.length
          },
          e: {
            r: R + rowspan - 1,
            c: outRow.length + colspan - 1
          }
        });
      };

      //Handle Value
      outRow.push(cellValue !== "" ? cellValue : null);

      //Handle Colspan
      if (colspan)
        for (var k = 0; k < colspan - 1; ++k) outRow.push(null);
    }
    out.push(outRow);
  }
  return [out, ranges];
};

function datenum(v, date1904) {
  if (date1904) v += 1462;
  var epoch = Date.parse(v);
  return (epoch - new Date(Date.UTC(1899, 11, 30))) / (24 * 60 * 60 * 1000);
}

/**
 * @param {*} data
 * @param {*} opts
 * 用于将二维数组转换为Excel工作表对象的JavaScript函数
 * 使用了XLSX.js库提供的工具方法来编码单元格引用和工作表范围，可生成可供Excel处理的工作表数据
 * 支持将一些数据类型转换为Excel支持的数据类型，例如将日期对象转换为数字类型，并设置相应的格式。
 * 链接：https://juejin.cn/post/7282950051319595066
 */
export function sheet_from_array_of_arrays(data) {
  var ws = {};
  var range = {
    s: {
      c: 10000000,
      r: 10000000
    },
    e: {
      c: 0,
      r: 0
    }
  };
  for (var R = 0; R != data.length; ++R) {
    for (var C = 0; C != data[R].length; ++C) {
      if (range.s.r > R) range.s.r = R;
      if (range.s.c > C) range.s.c = C;
      if (range.e.r < R) range.e.r = R;
      if (range.e.c < C) range.e.c = C;
      var cell = {
        v: data[R][C]
      };
      if (cell.v == null) continue;
      var cell_ref = XLSX.utils.encode_cell({
        c: C,
        r: R
      });

      if (typeof cell.v === 'number') cell.t = 'n';
      else if (typeof cell.v === 'boolean') cell.t = 'b';
      else if (cell.v instanceof Date) {
        cell.t = 'n';
        cell.z = XLSX.SSF._table[14];
        cell.v = datenum(cell.v);
      } else cell.t = 's';

      ws[cell_ref] = cell;
    }
  }
  if (range.s.c < 10000000) ws['!ref'] = XLSX.utils.encode_range(range);
  return ws;
}

function Workbook() {
  if (!(this instanceof Workbook)) return new Workbook();
  this.SheetNames = [];
  this.Sheets = {};
}

/**
 * 字符串转ArrayBuffer
 */
function s2ab(s) {
  var buf = new ArrayBuffer(s.length);
  var view = new Uint8Array(buf);
  for (var i = 0; i != s.length; ++i) view[i] = s.charCodeAt(i) & 0xFF;
  return buf;
}

export function export_table_to_excel(id) {
  var theTable = document.getElementById(id);
  var oo = generateArray(theTable);
  var ranges = oo[1];

  /* original data */
  var data = oo[0];
  var ws_name = "SheetJS";

  var wb = new Workbook(),
    ws = sheet_from_array_of_arrays(data);

  /* add ranges to worksheet */
  // ws['!cols'] = ['apple', 'banan'];
  ws['!merges'] = ranges;

  /* add worksheet to workbook */
  wb.SheetNames.push(ws_name);
  wb.Sheets[ws_name] = ws;

  var wbout = XLSXS.write(wb, {
    bookType: 'xlsx',
    bookSST: false,
    type: 'binary'
  });

  saveAs(new Blob([s2ab(wbout)], {
    type: "application/octet-stream"
  }), "test.xlsx")
}

/**
 * 单表头导出excel,无合并
 */
export function export_json_to_singleHeadExcel(th, jsonData, defaultTitle) {
  /* original data */
  var data = jsonData;
  console.log('th', th);
  console.log('jsonData', jsonData);
  console.log('defaultTitle', defaultTitle)
  data.unshift(th);
  var ws_name = "SheetJS";
  var wb = new Workbook(), ws = sheet_from_array_of_arrays(data);
  /*设置worksheet每列的最大宽度*/
  const colWidth = data.map(row => row.map(val => {
    /*先判断是否为null/undefined*/
    if (val == null) {
      return { 'wch': 10 };
    }
    /*再判断是否为中文*/
    else if (val.toString().charCodeAt(0) > 255) {
      return { 'wch': val.toString().length * 2 };
    } else {
      return { 'wch': val.toString().length };
    }
  }))
  /*以第一行为初始值*/
  let result = colWidth[0];
  for (let i = 1; i < colWidth.length; i++) {
    for (let j = 0; j < colWidth[i].length; j++) {
      if (result[j]['wch'] < colWidth[i][j]['wch']) {
        result[j]['wch'] = colWidth[i][j]['wch'];
      }
    }
  }
  ws['!cols'] = result;
  /* add worksheet to workbook */
  wb.SheetNames.push(ws_name);
  wb.Sheets[ws_name] = ws;
  var wbout = XLSX.write(wb, { bookType: 'xlsx', bookSST: false, type: 'binary' });
  var title = defaultTitle || 'excel-list'
  saveAs(new Blob([s2ab(wbout)], { type: "application/octet-stream" }), title + ".xlsx")
}

/**
 * 可单可多表头导出，无样式
 */
export function export_json_to_excel({
  multiHeader = [],
  header,
  data,
  filename,
  merges = [],
  autoWidth = true,
  bookType = 'xlsx'
} = {}) {
  /* original data */
  filename = filename || 'excel-list'
  data = [...data]
  data.unshift(header);

  for (let i = multiHeader.length - 1; i > -1; i--) {
    data.unshift(multiHeader[i])
  }

  var ws_name = "SheetJS";
  var wb = new Workbook(),
    ws = sheet_from_array_of_arrays(data);

  if (merges.length > 0) {
    if (!ws['!merges']) ws['!merges'] = [];
    merges.forEach(item => {
      ws['!merges'].push(XLSX.utils.decode_range(item))
    })
  }

  if (autoWidth) {
    /*设置worksheet每列的最大宽度*/
    const colWidth = data.map(row => row.map(val => {
      /*先判断是否为null/undefined*/
      if (val == null) {
        return {
          'wch': 10
        };
      }
      /*再判断是否为中文*/
      else if (val.toString().charCodeAt(0) > 255) {
        return {
          'wch': val.toString().length * 2
        };
      } else {
        return {
          'wch': val.toString().length
        };
      }
    }))
    /*以第一行为初始值*/
    let result = colWidth[0];
    for (let i = 1; i < colWidth.length; i++) {
      for (let j = 0; j < colWidth[i].length; j++) {
        if (result[j]['wch'] < colWidth[i][j]['wch']) {
          result[j]['wch'] = colWidth[i][j]['wch'];
        }
      }
    }
    ws['!cols'] = result;
  }

  /* add worksheet to workbook */
  wb.SheetNames.push(ws_name);
  wb.Sheets[ws_name] = ws;

  var wbout = XLSX.write(wb, {
    bookType: bookType,
    bookSST: false,
    type: 'binary'
  });
  saveAs(new Blob([s2ab(wbout)], {
    type: "application/octet-stream"
  }), `${filename}.${bookType}`);
}

/**
 * 带样式
 * multiHeader: 一级表头 
 * header: 二级表头
 * data: 表格的数据
 * filename: 导出的文件名称
 * specialCell: 需设置特殊样式的单元格数组
 * merges: 需要合并的每个单元格(不仅能合并表头单元格，还能合并表格内容单元格)数组
 * autoWidth: excel中每个单元格是否自动宽度(这个参数默认为true，而且也不建议设置为false，因为这将导致excel可读性非常差劲！)
 * bookType: 文件类型
 */
export function exportStyleExcel({
  multiHeader = [],
  header,
  data,
  filename,
  specialCell = [],
  merges = [],
  autoWidth = true,
  bookType = 'xlsx'
} = {}) {
  /* original data */
  filename = filename || 'excel-list'
  data = [...data]
  data.unshift(header);

  for (let i = multiHeader.length - 1; i > -1; i--) {
    data.unshift(multiHeader[i])
  }

  var ws_name = "SheetJS";
  var wb = new Workbook(),
    ws = sheet_from_array_of_arrays(data);

  if (merges.length > 0) {
    if (!ws['!merges']) ws['!merges'] = [];
    merges.forEach(item => {
      ws['!merges'].push(XLSX.utils.decode_range(item))
    })
  }

  if (autoWidth) {
    /*设置worksheet每列的最大宽度*/
    const colWidth = data.map(row => row.map(val => {
      /*先判断是否为null/undefined*/
      if (val == null) {
        return {
          'wch': 15
        };
      }
      /*再判断是否为中文*/
      else if (val.toString().charCodeAt(0) > 255) {
        return {
          'wch': val.toString().length * 3
        };
      } else {
        return {
          'wch': val.toString().length*1.5
        };
      }
    }))
    /*以第一行为初始值*/
    let result = colWidth[0];
    for (let i = 1; i < colWidth.length; i++) {
      for (let j = 0; j < colWidth[i].length; j++) {
        if (result[j]['wch'] < colWidth[i][j]['wch']) {
          result[j]['wch'] = colWidth[i][j]['wch'];
        }
      }
    }
    ws['!cols'] = result;
  }

  /* add worksheet to workbook */
  wb.SheetNames.push(ws_name);
  wb.Sheets[ws_name] = ws;

  var dataInfo = wb.Sheets[wb.SheetNames[0]];

  /**
   * 给所有单元格加上基础的居中、字体、字号等样式必须在最顶层；某些特殊样式在后面的操作中覆盖基本样式
   * 链接：https://juejin.cn/post/7093798005072986125
   * 链接：https://juejin.cn/post/6903820868859002888
   * !ref：表示工作表范围的字符串，worksheet['!ref'] = "A1:B5",整个表格的所有单元格开始到结束
   * !cols：存储列对象的数组，可以在这里设置列宽。
   *        //wpx 字段表示以像素为单位，wch 字段表示以字符为单位
   *        worksheet['!cols'] = [
   *           { wpx: 200 }, //设置第1列列宽为200像素
   *           { wch: 50 },  //设置第2列列宽为50字符
   *        ];
   * !merges：存储合并单元格范围的数组。
   *         //合并B2到D4范围内的单元格
   *         worksheet['!merges'] = [
   *           { 
   *             s: { c: 1, r: 1 }, //B2
   *             e: { c: 3, r: 3 }, //D4
   *            }]
   * !freeze：冻结单元格。
   *         //冻结第一行和第一列：
   *         worksheet['!freeze'] = {
   *            xSplit: "1",  //冻结列
   *            ySplit: "1",  //冻结行
   *            topLeftCell: "B2",  //在未冻结区域的左上角显示的单元格，默认为第一个未冻结的单元格
   *            state: "frozen"
   *         }
   *......-->https://cloud.tencent.com/developer/article/1635226         
   */
  /**
   * 给所有单元格添加边框、文字水平垂直居中
   */
  for (var i in dataInfo) {
    if (i == '!ref' || i == '!merges' || i == '!cols' || i == '!rows') { } else {
      dataInfo[i + ''].s = {
        border: {
          top: { style: 'thin'},
          bottom: { style: 'thin'},
          left: { style: 'thin'},
          right: { style: 'thin'},
        },
        alignment: { horizontal: 'center', vertical: 'center' },
      }
    }
  }
  /**
   * 给特殊单元格加样式，覆盖基础样式
   */
  for (var i = 0; i < specialCell.length; i++) {
    dataInfo[specialCell[i].type].s = { ...dataInfo[specialCell[i].type].s, ...specialCell[i].s };
  }

  var wbout = XLSXS.write(wb, {
    bookType: bookType,
    bookSST: false,
    type: 'binary'
  });

  saveAs(new Blob([s2ab(wbout)], {
    type: "application/octet-stream"
  }), `${filename}.${bookType}`);

}

